The Agency for Healthcare Research and Quality (AHRQ), the Centers for Disease Control and Prevention (CDC), and the Centers for Medicare and Medicaid Services (CMS) have all expressed interest in developing validated quality measures for inter-hospital comparisons of healthcare associated infections, including surgical site infections (SSIs). AHRQ's claims-based quality indicators have been applied to administrative data collected through the Healthcare Cost and Utilization Project. Medicare has begun implementation of a value-based purchasing program which will include deep incisional and organ/space SSIs reported by hospitals using the CDC's National Healthcare Safety Network (NHSN). Hospitals reporting higher SSI risks will receive lower reimbursement. Thus, there is a need for improved surveillance and validated quality measures targeting high-risk surgeries, both in major surgical centers and in hospitals with lower procedure volumes. Claims data have been shown to provide more standardized and comprehensive capture compared to traditional SSI surveillance by hospital infection control programs. We propose to expand our prior work on the use of claims data for SSI surveillance by targeting procedures mandated by states for public reporting and proposed for value-based purchasing by CMS. We will 1) extend our previously successful claims-based surveillance following coronary artery bypass graft (CABG) surgery and hip arthroplasty to identify hospitals with an unusually high risk of SSI following knee arthroplasty, another high volume and high cost procedure, 2) identify and validate claims-based methods for estimating the risk of deep incisional and organ/space infections following CABG surgery, hip arthroplasty, and knee arthroplasty, and use these methods to determine year-to-year predictive utility of hospital rankings, 3) assess the generalizability of hospital SSI rankings using Medicare claims compared to hospital rankings derived from all-payer claims databases, and from rankings based on state mandated reporting to NHSN, and 4) evaluate statistical approaches to evaluate the performance of hospitals with low procedure volumes.